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This explosion of knowledge has yet to produce much practical fallout for the majority of today's retardation victims, or for those who will soon be born. While diagnostic techniques have improved, making earlier recognition possible more often, inadequate medical and educational services still prevent many children from getting expert help soon enough to make a difference. Though more physicians, educators and psychologists have become interested in the subject recently, many who were trained years ago are still unskilled in dealing with the child and counseling his parents. The development of antibiotics and the rapid improvement in procedures that save the lives of sick infants, meanwhile, have allowed more of the retarded to survive childhood. Thus their number is likely to increase, at least for the short term.
Cultural Causes. Though there are more than 200 known causes, the disability can be divided into two broad but somewhat arbitrary categories.
The first group consists mainly of people rated as severely or profoundly retarded—those with IQs ranging from 30 down. Usually these people, like Tracy Albertsen, have clearly detectable physical flaws. Some suffer from chromosomal abnormalities, such as Down's syndrome, or mongolism. Others have genetic problems such as phenylketonuria (PKU), a condition caused by lack of an essential enzyme. Still others acquire congenital infections like syphilis or are affected by German measles contracted by the mother.
The second group is made up mostly of those called moderately and mildly retarded, with IQs of between 30 and 75. They are for the most part medical mysteries, like the Leonard brothers, who appear to have no physical defects. Some have suffered birth injuries that produce slight brain damage, the effects of which appear years later. Most seem to be casualties of their environment, starting with the womb, their disabilities the result of a congeries of medical, cultural and economic causes.
Cat's Cry. Science at present understands the more serious forms of retardation better than the less serious ones. Chromosomal problems like mongolism or cri-du-chat (cat's cry) syndrome, which leaves an infant with a partially developed head and brain and a peculiar mewing voice, can be spotted almost immediately after birth.
None of these severe conditions can yet be cured. But as a result of recent scientific developments, many can be prevented. German measles, responsible for the birth of many retarded infants, has been nearly eliminated thanks to a nationwide immunization campaign. PKU's effects can be checked by a special diet if the defect is immediately identified; 43 states now require a PK.U test at birth. Doctors can recognize the chromosomal flaw that causes mongolism and 27 of the genetic quirks known to cause retardation. More important, they can diagnose these in the fetus by amniocentesis. A needle is inserted into the uterus to draw off a sample of the fluid in which the fetus floats. The material is analyzed for extra or missing chromosomes or absent enzymes.